Composition sensitive to visible light

ABSTRACT

The present invention provides a visible light-sensitive composition which is highly sensitive to a visible light and is useful as an electronic circuit forming material, a lithographic printing material, etc., said visible light-sensitive composition comprising (a) a polymer comprising a repeating unit represented by general formula (I):  
                 
 
wherein R 1 , R 2 , and R 3  are the same or different and each represents substituted or unsubstituted alkyl, substituted or unsubstituted aryl, or substituted or unsubstituted aralkyl, or alternatively R 1  and R 2  form cycloalkyl together with the adjacent carbon atom, and R 4  represents lower alkyl, (b) a compound that generates an acid by visible light irradiation and (c) a sensitizing dye.

TECHNICAL FIELD

The present invention relates to a visible light-sensitive compositionuseful for an electronic circuit forming material, a lithographicprinting material, production of a filter for a color display devicesuch as a liquid crystal display or a plasma display, etc.

BACKGROUND ART

Recently, positive photoresists have been widely used for formingelectronic circuit patterns, and in most of the positive photoresists acomposition containing a novolak resin and a naphthoquinone diazidecompound as a photosensitive agent is used. In the composition, thenovolak resin can be dissolved in an aqueous alkaline solution withoutswelling. The naphthoquinone diazide compound acts to reduce the alkalisolubility of the novolak resin, while the compound is decomposed byirradiation of ultraviolet ray, etc. and converted into indenecarboxylic acid to increase the alkali solubility of the novolak resin,and thus the composition is useful as the positive photoresist. However,this composition is poor in reactivity to a visible light, anddisadvantageous in that sufficient resolution cannot be achieved in thecase of forming a fine pattern.

Photosensitive compositions comprising a compound capable of generatingan acid by light irradiation, a compound having a group derived from apolyfunctional vinyl ether compound, etc., are disclosed inJP-A-6-295064, JP-A-7-146552, JP-A-11-153858, and JP-A-11-174680.However, these compositions have disadvantages of poor yield, which isdue to decrease of thermal crosslinking efficiency by diffusionlimitation, and poor storage stability.

Also in the field of planography, in recent years there has beenincreasing interest in lithographic printing materials capable ofdirectly plate-making using a visible laser or an infrared laser insteadof conventional systems utilizing an ultraviolet light. JP-A-7-186562and WO 02/11996 disclose photothermal type positive plate-makingmaterials using an infrared laser. However, since these materials use along wavelength laser as a light source, these materials aredisadvantageous in view point of obtaining high resolution.

As a stable, high-energy laser, which is presently used in the aboveapplications, those having an output wavelength within the visibleregion are often used, and examples thereof include an argon ion laserhaving oscillation lines at the wavelengths of 488 nm and 514.5 nm and aYAG laser having an emission line at 532 nm as the second high harmonicwave. Accordingly, there is a demand for a compound having a highsensitivity to these wavelengths.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a photosensitivecomposition having a high sensitivity to a visible light, which isuseful as an electronic circuit forming material, a lithographicprinting material, etc.

The present invention provides the following (1) to (4).

(1) A visible light-sensitive composition comprising (a) a polymercomprising a repeating unit represented by general formula (I):

wherein R¹, R² and R³ are the same or different and each representssubstituted or unsubstituted alkyl, substituted or unsubstituted aryl,or substituted or unsubstituted aralkyl, or alternatively R¹ and R² formcycloalkyl together with the adjacent carbon atom, and R⁴ representslower alkyl, (b) a compound that generates an acid by visible lightirradiation, and (c) a sensitizing dye.

(2) The visible light-sensitive composition according to (1), whereinthe polymer comprising a repeating unit represented by general formula(I) has a number average molecular weight of 1,000 to 100,000.

(3) The visible light-sensitive composition according to (1) or (2),which comprises 0.1 to 40 parts by weight of the compound that generatesan acid by visible light irradiation per 100 parts by weight of thepolymer comprising a repeating unit represented by general formula (I).

(4) The visible light-sensitive composition according to any one of (1)to (3), which comprises 0.1 to 10 parts by weight of the sensitizing dyeper 100 parts by weight of the polymer comprising a repeating unitrepresented by general formula (I).

In the definitions of the groups in general formula (I), the alkylincludes straight or branched alkyl having 1 to 18 carbon atoms, andspecific examples thereof are methyl, ethyl, propyl, isopropyl, butyl,isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl,decyl, dodecyl, octadecyl, etc, among these, the alkyl having 1 to 6carbon atoms is preferred, and the alkyl having 1 to 3 carbon atoms ismore preferred.

The lower alkyl includes straight or, branched alkyl having 1 to 8carbon atoms, and examples thereof are methyl, ethyl, propyl, isopropyl,butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl,etc.

The cycloalkyl formed by R¹ and R² together with the adjacent carbonatom includes cycloalkyl having 3 to 8 carbon atoms, and examplesthereof are cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl,cycloheptyl, cyclooctyl, etc.

The aryl includes aryl having 6 to 12 carbon atoms, and examples thereofare phenyl, naphtyl, etc.

The aralkyl includes aralkyl having 7 to 15 carbon atoms, and examplesthereof are benzyl, phenethyl, naphtylmethyl, naphtylethyl, etc.

Examples of the substituents in the substituted alkyl are lower alkoxy,lower alkanoyl, cyano, nitro, halogen, lower alkoxycarbonyl, etc.Examples of the alkyl moieties of the lower alkoxy, the lower alkanoyl,and the lower alkoxycarbonyl are the same as those of the lower alkyldescribed above. The halogen means, fluorine, chlorine, bromine, andiodine atoms.

Examples of the substituents in the substituted aryl and the substitutedaralkyl include lower alkyl, lower alkoxy, lower alkanoyl, cyano, nitro,halogen, lower alkoxycarbonyl, etc. Examples of the lower alkyl, thelower alkoxy, the lower alkanoyl, the halogen, and the loweralkoxycarbonyl are the same as described above, respectively.

The polymer comprising the repeating unit represented by general formula(I) may be produced by subjecting that an unsaturated ester representedby the general formula (IV):

wherein R¹, R², R³, and R⁴ have the same meaning as defined to radicalpolymerization or ionic polymerization above, each is polymerized singlyor with the other copolymerizable monomer according to a methoddescribed in Shin Kobunshi Jikkengaku 2, Kobunshi no Gosei Hanno (1),edited by The Society of Polymer Science, Japan, pages 1 to 224, Jun.15, 1995, etc. Examples of the other copolymerizable monomers includearomatic vinyl compounds such as styrene and hydroxystyrene;α,β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid,itaconic acid, mesaconic acid, maleic acid, and fumaric acid;α,β-unsaturated esters such as methyl acrylate, methyl methacrylate,hydroxyethyl acrylate, and hydroxyethyl methacrylate; etc.

The polymer comprising the repeating unit represented by general formula(I) is hereinafter referred to as polymer (I) in some cases.

In the production of polymer (I), the unsaturated ester represented bygeneral formula (IV) is used 10% in an amount of preferably by weight ormore, more preferably 20% by weight or more, based on the total amountof the monomers used.

The number average molecular weight of polymer (I) is preferably 1,000to 100,000, more preferably 5,000 to 50,000.

As the compound that generates an acid by visible light irradiation,preferably used are compounds represented by general formula (II):

wherein R⁵ represents substituted or unsubstituted alkyl, substituted orunsubstituted aryl, or substituted or unsubstituted aralkyl. Examples ofthe substituted or unsubstituted alkyl, the substituted or unsubstitutedaryl, and the substituted or unsubstituted aralkyl are the same as thosedescribed above.

In the compounds represented by general formula (II), R⁵ is preferablymethyl, trifluoromethyl, or p-methylphenyl, and more preferablytrifluoromethyl.

The compound that generates an acid by visible light irradiation ishereinafter referred to as the photo-acid-generating agent in somecases.

As the sensitizing dye, preferably used are compounds represented bygeneral formula (III):

wherein R⁶ and R⁷ are the same or different and each represent ahydrogen atom or lower alkyl. Examples of the lower alkyl are the sameas those described above. In the compounds represented by generalformula (III), compounds wherein R⁶ and R⁷ are the same or different andeach represents a hydrogen atom or ethyl are preferably used. Thesensitizing dyes may be produced by a method described in U.S. Pat. No.4,916,711, U.S. Pat. No. 5,189,029, etc.

The visible light-sensitive composition of the present inventioncontains polymer (I), the photo-acid-generating agent, and thesensitizing dye, but there are no particular restrictions on the methodand order of mixing the components.

The photo-acid-generating agent is used in an amount of preferably 0.1to 40 parts by weight, more preferably 0.2 to 20 parts by weight,further preferably 0.5 to 15 parts by weight, based on 100 parts byweight of polymer (I).

The sensitizing dye is used in an amount of preferably 0.1 to 10 partsby weight, more preferably 0.2 to 5 parts by weight, further preferably0.5 to 3 parts by weight, based on 100 parts by weight of polymer (I).

The visible light-sensitive composition of the present invention maycontain a solvent, and examples thereof include hydrocarbon solventssuch as hexane, toluene, and xylene; ether solvents such as dioxane andtetrahydrofuran; ketone solvents such as acetone, methyl ethyl ketone,methyl isobutyl ketone, and cyclohexanone; alcohol solvents such asisopropyl alcohol, butanol, hexanol, octanol, and benzyl alcohol; glycolsolvents such as ethylene glycol, propylene glycol, ethylene glycolmonomethyl ether, ethylene glycol monoethyl ether, propylene glycolmonomethyl ether, propylene glycol monoethyl ether, propylene glycolmonomethyl ether acetate; etc. These solvents may be used alone or as amixture of 2 or more solvents, and the solvents is used in an amount ofpreferably 1 to 100 parts by weight per one part by weight of polymer(I).

Pattern formation using the visible light-sensitive composition of thepresent invention may be carried out in the following manner. First, thevisible light-sensitive composition of the present invention is appliedonto a substratum such as an aluminum plate, a copper plate, and asilicon wafer by a spin coating method, a bar coating method, or a spraycoating method, and is heated preferably at 80 to 130° C. for 1 to 30minutes for drying a coating film. Then, the coating film formed on thesubstratum is irradiated imagewise with a visible light using a positivephotomask, a reduced projection exposure apparatus, a direct drawingapparatus, etc. As, the visible light, preferably used are an argon ionlaser having oscillation lines at the wavelengths of 488 nm and 514.5nm, a YAG laser having an emission line of a second high harmonic waveat 532 nm, etc.

After the visible light irradiation, the coating film is preferablyheated at 50 to 150° C. for 1 to 30 minutes, and then developed by usingan alkaline solution of tetramethylammonium hydroxide (TMAH), analkanolamine such as ethanolamine, an inorganic alkali such as sodiumhydroxide, sodium carbonate, sodium hydrogen carbonate, and sodiummetasilicate, etc.

As a result, a positive pattern with an excellent dimensional accuracyand a high resolution is formed on the surface of substratum.

The pattern formed in this manner is useful for forming an electroniccircuit, a lithographic printing plate, a filter for a color displaysuch as a liquid crystal display and a plasma display, etc.Particularly, the visible light-sensitive composition of the presentinvention is remarkably high in the sensitivity, and by using thevisible light-sensitive composition of an exposure time is shortened toincrease the working efficiency and a finer pattern can be formed.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in more detail below withreference to Examples and Reference Examples.

In Reference Examples, number average molecular weights (Mn) of polymerswere measured by a gel permeation chromatography under the followingconditions. Column: Two TSKgel Super HM-M columns and one HM-H column(both available from Tosoh Corporation) connected in series.

-   Column temperature: 40° C.-   Detector: RI-   Developing solvent: Tetrahydrofuran (flow rate 0.5 ml/minute)-   Reference substance: Polystyrene

Sensitivities of photosensitive compositions were calculated using thefollowing equation:Sensitivity I _(o)×10^(−A) ×t

-   I_(o): Exposure intensity (mJ/cm² second)-   A: Optical density of step tablet-   t: Exposure time (second)

REFERENCE EXAMPLE 1 Synthesis of Polymer A

8.5 g of 1-n-propoxy-2-methylpropyl methacrylate, 25.0 g of methylmethacrylate, and 1.1 g of 2,2′-azobis(2-methylbutyronitrile) (AMBN)were dissolved in 15.0 g of methyl isobutyl ketone. The mixture wasadded dropwise to 35.0 g of methyl isobutyl ketone heated at 70° C. over2 hours, and polymerized at 70° C. for 3 hours. Then, 83.0 g of methylisobutyl ketone was added to the reaction mixture and cooled to the roomtemperature. The resultant reaction mixture was added to 3 L of methanoldropwise at the room temperature to precipitate a polymer, and thenfiltered to obtain 20.8 g of the polymer having a number averagemolecular weight of 16,000.

REFERENCE EXAMPLE 2 Synthesis of Polymer B

7.3 g of 1-n-methoxy-2-methylpropyl methacrylate, 22.1 g of methylmethacrylate, 4.1 g of 2-hydroxyethyl methacrylate, and 1.1 g of AMBNwere dissolved in 15.0 g of propylene glycol monomethyl ether acetate(PMA). The mixture added dropwise to 35.0 g of PMA heated at 70° C. over2 hours, and The monomers were polymerized at 70° C. for 3 hours, andthen 83.0 g of PMA was added to the reaction mixture and cooled to theroom temperature. The resultant reaction mixture was added dropwise to 3L of methanol at the room temperature to precipitate a polymer, andfiltered to obtain 21.2 g of the polymer having a number averagemolecular weight of 13,500.

EXAMPLE 1 Production and Evaluation of Photosensitive Composition

100 parts by weight of polymer A synthesized in Reference Example 1 wasdissolved in 466 parts by weight of cyclohexanone, and to 1 part byweight of4,4-difluoro-1,3,5,7,8-pentamethyl-4-bora-3a,4a-diaza-s-indacene and 5parts by weight of NAI-105 (a photo-acid-generating agent, availablefrom Midori Kagaku Kogyo Co., Ltd.) were added thereto to prepare aphotosensitive composition. The photosensitive composition was appliedonto an aluminum plate, which had been subjected to grinding andanodizing treatment, using a spin coating method, and prebaked at 100°C. for 10 minutes, to obtain a photosensitive layer having a thicknessof about 1 μm. A step tablet was adhered to the obtained photosensitivelayer, and the obtained layer was irradiated with an argon ion laser(Spectraphysic Stabilite 2016) having an intensity of 2.0 mJ/cm² second,heated at 120° C. for 10 minutes, and developed for 1 minute by using amixture of a 2.38 weight % aqueous solution of tetramethylammoniumhydroxide and isopropyl alcohol (mixing ratio 1/1). Then, the minimumenergy amount required for the photosensitization was obtained as asensitivity from a step with the maximum density, in which the polymerfilm of the photosensitive layer was dissolved. The sensitivity of thephotosensitive composition was 0.52 mJ/cm² to the wavelength of 488 nm,and 1.22 mJ/cm² to the wavelength of 514.5 nm.

EXAMPLE 2 Production and Evaluation of Photosensitive Composition

100 parts by weight of polymer A synthesized in Reference Example 1 wasdissolved in 466 parts by weight of cyclohexanone, and 1 part by weightof2,6-diethyl-4,4-difluoro-1,3,5,7,8-pentamethyl-4-bora-3a,4a-diaza-s-indaceneand 5 parts by weight of NAI-105 (a photo-acid-generating agent,available from Midori Kagaku Kogyo Co., Ltd.) were added thereto toprepare a photosensitive composition. The photosensitive composition wasapplied onto an aluminum plate, which had been subjected to grinding andanodizing treatment, using a spin coating method, and then prebaked at100° C. for 10 minutes, to obtain a photosensitive layer having athickness of about 1 μm. A step tablet was adhered to the obtainedphotosensitive layer, and the obtained layer was irradiated with anargon ion laser (Spectraphysic Stabilite 2016) having an intensity of2.0 in J/cm²·second, heated at 120° C. for 10 minutes, and developed for1 minute by using a mixture of a 2.38 weight % aqueous solution oftetramethylammonium hydroxide and isopropyl alcohol (mixing ratio 1/1).Then, the minimum energy amount required for the photosensitization wasobtained as a sensitivity from a step with the maximum density, in whichthe polymer film of the photosensitive layer was dissolved. Thesensitivity of the photosensitive composition was 1.58 mJ/cm² to thewavelength of 488 nm, and 1.97 mJ/cm² to the wavelength of 514.5 nm.

EXAMPLE 3 Production and Evaluation of Photosensitive Composition

100 parts by weight of polymer B synthesized in Reference Example 2 wasdissolved in 466 parts by weight of PMA, and 0.1 part by weight of2,6-diethyl-4,4-difluoro-1,3,5,7,8-pentamethyl-4-bora-3a,4a-diaza-s-indaceneand 5 parts by weight of NAI-105 (a photo-acid-generating agent,available from Midori Kagaku Kogyo Co., Ltd.) were added thereto toprepare a photosensitive composition. The photosensitive composition wasapplied onto an aluminum plate, which had been subjected to grinding andanodizing treatment, using a spin coating method, and prebaked at 100°C. for 5 minutes, to obtain a photosensitive layer having a thickness ofabout 1 μm. A step tablet was adhered to the obtained photosensitivelayer, and the obtained layer was irradiated with an argon ion laser(Spectraphysic Stabilite 2016) having an intensity of 2.0 mJ/cm² second,heated at 120° C. for 5 minutes, and developed for 1 minute by using amixture of a 2.38 weight % aqueous solution of tetramethylammoniumhydroxide and isopropyl alcohol (mixing ratio 7/3). Then, the minimumenergy amount required for the photosensitization was obtained as asensitivity from a step with the maximum density, in which the polymerfilm of the photosensitive layer was dissolved. The sensitivity of thephotosensitive composition was 0.90 mJ/cm² to the wavelength of 488 nm.

INDUSTRIAL APPLICABILITY

According to the present invention, a photosensitive composition whichis highly sensitive to a visible light, and is useful as an electroniccircuit forming material, a lithographic printing material, etc.

1. A visible light-sensitive composition comprising (a) a polymercomprising a repeating unit represented by general formula (I):

wherein R¹, R² and R³ are the same or different and each representssubstituted or unsubstituted alkyl, substituted or unsubstituted aryl,or substituted or unsubstituted aralkyl, or alternatively R¹ and R² formcycloalkyl together with the adjacent carbon atom, and R⁴ representslower alkyl, (b) a compound that generates an acid by visible lightirradiation, and (c) a sensitizing dye.
 2. The visible light-sensitivecomposition according to claim 1, wherein the polymer comprising arepeating unit represented by general formula (I) has a number averagemolecular weight of 1,000 to 100,000.
 3. The visible light-sensitivecomposition according to claim 1 or 2, which comprises 0.1 to 40 partsby weight of the compound that generates an acid by visible lightirradiation per 100 parts by weight of the polymer comprising arepeating unit represented by general formula (I).
 4. The visiblelight-sensitive composition according to claim 1 or 2, which comprises0.1 to 10 parts by weight of the sensitizing dye per 100 parts by weightof the polymer comprising a repeating unit represented by generalformula (I).
 5. The visible light-sensitive composition according toclaim 3, which comprises 0.1 to 10 parts by weight of the sensitizingdye per 100 parts by weight of the polymer comprising a repeating unitrepresented by general formula (I).